Electrostatically-focused rotary radial beam tube



Oct. 28, 1952 p w 0 2,616,061

ELECTROSTATICALLY-FOCUSED ROTARY RADIAL BEAM TUBE Filed sept. 16, 1950 3 Sheets-Sheet 1 Zfiaq. E. Q g

IN VEN TOR.

A TTOENEV Oct. 28, 1952 P. w. CHARTON ELECTROSTATICALLY-FOCUSED ROTARY RADIAL BEAM TUBE Filed Sept. 16, 1950 3 Sheets-Sheet 2 INVEN TOR. 8404 M CHA/QTO/V A TTOE/VE'V Filed Sept. 16, 1950 Oct. 28, 1952 P. w. CHARTON 2,616,061

ELECTROSTATICALLY-FOCUSED ROTARY RADIAL BEAM TUBE 3 Sheets-Sheet 3 IN V EN TOR. 8404 W OVA/970M A TTOE/VEV Patented Oct.- 28, 1952 res ELEGTROSTATICALLY-FOCUSED ROTARY RADIAL BEAM TUBE Paul W. Charton, Montclair, N. 3., assignor to National Union Radio Corporation, Orange, N. .L, a corporationof Delaware Application September 16, 1950, Serial No. 185,280

7 15 Claims.

This invention relatesqto rotary beam tubes,

and more especially to rotary beam tubes of the electrostatically focussed beam category.

The invention is in the nature of an improvement on the kind of tube disclosed in U. S.-

' at a uniform rate around the longitudinal axis of the cathode. Each window or slot in and between adjacent screens is in radial alignment with a correspondin control grid andoutput anode combination which may be allotted to respective output channels. Such a tube is ideally suited to multiplex telegraphy and telephony,

and to telemetering and many other fields of usefulness.

The type of tube disclosed in said prior patent, employs insulating spacers or mica discs at opposite endsof the electrode assembly to preserve the proper interelectrode spacings. I have found that by reason of the physical relation between the emitting cathode and the 'said spacers, the latter tend to become electrically charged, which charge may be unevenly distributed thereover. This unevenly distributed charge may cause a very undesirable distortion of the required symmetrical field between the various electrodes and more particularly between the cathode and the surrounding screens.

This causes, among other things, a reduction in the beam height, a reduction in the beam current, and an uneven rate of rotary displacement of the beam. These undesirable effects are more pronounced in those radial beam tubes wherein 'the ratio of the effective cathode length to the radial distance between the cathode and screens is large.

Accordingly, one of the principal objects of this .invention is to provide improved constructions of focussed rotary radial beam tubes which overcome the above-noted and other disadvantages.

Another limitation on the type of focussed rotary radial beam tube as disclosed in said patent, .is thatthe number of multiple output channels that can be efiectively used, is tied up with the structural limitations of the tube. One of these $5.

2 limitations is .thatthe screens are connected to the polyphase source to control the rate of beamrotation. Since serious design difliculties are encountered if the number of channels is not a multiple of the number of phases, and since excitation sources of more than six phases are difiicult to design and handle, for practical purposes the prior tube is limited to six, or multiples of six, output channels.

Accordingly, it is another principal object of this invention to provide a construction of a focussed rotary radial beam tube wherein the number of output channels is not limited by the number of phases of the polyphase excitation source. For example, a two-, three-, or sixphase source can be used, and any number of output channels can be controlled.

Another object is to provide a focussed rotary radial beam tube employing a central cathode anda plurality of vertically-stacked beam focussing and rotating sections.

A feature of the invention relates to a tube of the focussed rotary radial beam type, having a series of slotted screen segments each having electrically attached thereto at opposite ends, electrically conductive flanges or radially-directed extensions to restore: the height of the beam after such height has been reduced by the means which is also provided according to the invention to overcome the above-noted undesirable charges on the mica spacers.

-Another feature relates to a focussed rotary radial beam tube wherein the channel-defining screens can be formed of a single circumferentially complete plate with the desired number of channel-defining slots therein. The rate of rotation of the beam is then controlled by a relatively smaller number of conductive plates extending perpendicularly and radially to the cathode, and which plates can be excited by a suitable polyphase source to effect rotation of the beam.

A still further feature relates to the novel organization. arrangement and relative location of parts which cooperate to provide a simplified and improved tube of the focussed rotary radial beam type.

Other features and advantages, not specifically enumerated, will become apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing,

Fig. 1 is a perspective view of certain parts of a focussed rotary radial beam tube useful in explaining the invention.

Fig. 2 shows an arrangement, according to the invention, for overcoming the beam distortion shown in Fig. 1.

Fig. 3 shows a modification of Fig. 2, wherein additional means are provided for overcoming the beameheight reduction shown in Fig. 2.

Fig. (l is, a detail perspective view of one vof the slotted screen elements of Fig. 3 showing its integral elements for restoring the beam height.

Fig. 5 is a plan schematic view of a tube embodying the improvements of Figs, 2 and 3..

Fig. 6 is a front elevational view of a modifis cation of Fig. 5.

Fig. 7 is a sectional view of Fig, 6, ,talren along the line thereof.

Fig. 8 is a composite perspective and schematic view of certain parts of the'tu'be'of'Figs; 6 and 7, to illustrate more clearly certain electricalcom nections.

F g. 9 is an e nel c em tic iew .o a modiflcati n. applicable either to the tube 01," Figs. gto 5, or to the tube of -Figs; 6 to 8.

Referring to 1, there is shown in perspective and schematic form, a portion of a typical i'ocussed rotary radial beam tube. For simplicity, Fig, 1 shows merely the central electron-emitting cathode I 0 and 2 of the surrounding slotted screen electrodes l I, [2, etc., with their respective channel-defining windows or slots l3, M. For a detailed description of the remaining elements of such a tube, reference may be had to said U. S. Letters Patent No. 2,433,403. As describedin detail in said patent, when the cathode l 0 is-suitably biased, and the screens ll, l2, etc. are connected to a suitable polyphase source, the electrons from the cathode are formed into a sheet-like radiallyextending beam which rotates at a rate determined bythe polyphase source. I have found that, depending upon the voltages that are used and upon the configurations of the. various tube electrodes, the insulator: or mica spacers t6, II, which are used to space the electrodes, become unevenly charged, as represented. schematically by the stippled areas l8, [9, 20 These uneven charges produce a corresponding uneven electrostatic field acting on the electron sheet, so that its desired planar sheet-like form is distorted. This distortion may eflecta reduction in the beam height h at the region where the beam intersects the screens H', l2. etc. duringits rotation. It also may reduce the amountv or beam. current flowing to. the output anodes, and mayeven prevent. uniform rotary displacement of the beam.

In accordance with one feature fo. theinvention, each of: the insulator discs Hi, [71; as shown in Fig. 2, carries, at. its central region surrounding the ends of the cathode, a pair of conductor discs 2], 22 These discs may be in the form of metal members suitably fastened to. the: respective i at rs, or they' may be th f rm of; conductive coatings, deposited on. the said insulators. The conductive discs 2|, 22 are insulated from the cathode s e veancl for hat purpos they m y be n. h m of: annular memb rs or atin s. W le e d aw s ow t ememberszl a d H q r la 'o nula ve ments. it wi lbeunderstcod that any other desired shape may be; employed. However, sincethebeam is to rotate. at auniform rate, it ispreferable to: make. the elements.- 231., 22 of symmetrical annular conformation around the cathode. The members 2.1, and: 2.2 are connected together by a suitable conductor 2? which is connected to. the adjustable arm 2t of a potentiometer resistance 25, connected to a direct current bias source. The source 26: is so connected that by adjusting the arm 24, the members 2! and 22 are biased negatively with respect to the oathode. As a result, the beam I5 is rendered symmetrical both at its upper and lower edges, and its planar shape is preserved during rotation.

While the arrangement of Fig. 2 results in a uniformly-focussed and uniformly-rotated beam, it has the disadvantage that the portion of the beam h at the region where it intersects the screen electrodes II, I 2, etc., is less than the height of 13118 corresponding screen slots or windows. In other 'words, the members 2| and 22 tend to compress the beam to a height h which is appreciably smaller than the effective length lot the cathode.

3'showsan arrangement whereby this height compression can be overcome. In Fig. 3, each 01. the. slotted. screen electrodes has electrically connected to it, at its upper and lower ends, a

pair of radially and inwardly extending conduct.

ing sectors or flanges 21, 28, etc. Preferably these flanges are welded or otherwise integrally attached .to the respective. screen: elements, one-of which is shown in perspective in Fig. 4. These flanges or sectors are of course separate from each other, as are the slotted screens. themselves. Since each of the screen electrodes is, during a certain portion of the polyphase supply cycle, at a, positive potential as explained in said publication, the flanges 21, 28, etc. are, therefore also positive at the same instantthat the beam is in radial alignment with the corresponding window or slot. This positive potential. on the flanges tends to restore the height h of the beam, as shown in Fig. 3. A the same time, it results in an increased beam current, and. maintains uniformity of rotation of thebeam.

One of the limitations on, the type of tube shown in Figs. 1-5 is that the number of output channels is fixe b thenumber of phases. of the polyphase source. Thus as shown .in Fig. 5, the tube is designed to be operated. from a threephase Qrwsixephasesource, Or even. from a sing-lephase source. which isefiectively split into; Six phases as illustrated in Fig. '7 of the. saidpublica tion. (Jonsequently six slotted screen electrodes with their upper and lower beam-restoring flanges are, used. since the space between theedges of adjacent screen. electrodesis also. used as a channeldefining slot, it is, ossible, to use, twelve output channels, each comprising a signal control grid 29, and. itsv respective output, anode. 30-. In. any event. the number oioutput han e must ar an integral relation to, the number-of phases used to theex itation. 0.1. the creen electrodes; to rotate the beam. In. somev casesit. may be. desirable to have a non-integral, relation. For. example, Where a three-phase or, six-phase source is. avai1- able, it may be. required to have eleven, twentyone, or som other non-integral number of output channels.

Figs. 6, '7 and 8 show a tube, whereinv this result can be accomplished. The parts, of thetube. of

Figs. 6 to 8 which are identical. with those. of.

Fig. 5', bear thesame designationnumerals- The main point of. duierence isthatin the. tube. of Figs. 6 to 8, instead of using a series of discrete arcuatershapcd. slotted screen, electrodes, a single continuous. metal plate 3| is. employed, having the. requir d number. of slots. 32 therein: corresponding to the number of. output channels. Each of? these; slotsis; in radial alignmentwith the corresponding control g-rictifli and output anode 30: of its respective channel. In order to be able to. use a greater and non-integral number of channel-defining slots 32 as compared with the number of phasesin the polyphase supply, the flanges 27, 28, instead of being electrically connected to the slotted electrode 3!, are insulated or separate therefrom. Each pair of upper and lower flanges is connected together electrically by a conductor, and these conductors are connected to a suitable polyphase supply 33 (Fig. 8). A single separate conductor 34 is provided for the single continuous slotted electrode 3|, which may be connected to a suitable positive direct current potential 35.

Fig. 9 shows a still further modification, wherein the tube may be constituted of a series of vertically-stacked sections. A single continuous electron-emitting cathode 36 may be provided for all the sections. The remaining elements of Fig. 9 which perform the same function as those of the preceding figures are designated alike. Thus in Fig. 9, the cathode 36 at each section is provided with charge neutralizing plates 2i, 22, and with respective beam-restoring plates or flanges 21, 28, similar to those illustrated in Figs. 3 to 8. A single slotted shield electrode 3|, similar to the corresponding electrode of Fig. 8, is connected to a suitable direct current supply as in Fig. 8. The vertically-aligned flanges 27, 28, for each section, are connected in multiple to a corresponding conductor 31, Likewise the corresponding verticallyaligned beam-restoring flanges are connected torespective similar conductors 31, and thence to a polyphase source such as the source 33. The vertically-aligned slots in the screen electrode 3| have in alignment therewith, a corresponding grid 38 which extends vertically past all the stacked sections. Likewise in radial alignment with each grid 38 is a corresponding output anode 39. In other words, the tube of Fig. 9 will be constructed by vertically superposing three sections similar to that shown in Fig. 8, and by extending each of the grids and anodes shown in Fig. '7 so that they are in alignment respectively with the vertically-aligned slots in the electrode 3|. It will be understood that it is not necessary to have each grid and its corresponding anode as a continuous one-piece element extending past the windows in the successive tiers or levels. Each window in each tier may have an individual grid and anode so that all the windows can then be used to define separate respective channels at each tier or level.

While certain embodiments have been described herein, it will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In an electron tube and in combination, a central electron-emitting cathode, channel-defining screen electrode means surrounding said cathode to form the electrons from the cathode into a focussed sheet-like beam, insulator spacer means to maintain a predetermined spaced relation between the cathode and screen electrode means, annular cnnductive means carried by said insulator means surrounding the ends of the cathode but restricted to the central region of said insulator means, and separate lead-in means for said conductive means for applying a positive potential thereto to dissipate undesired electric charges on said insulator means which tend to distort said beam.

2. An electron tube according to claim 1, in which each of said conductive means is in the form of an annular disc attached to the corre- 6, sponding one of said insulators butsurrounding the cathode in spaced relation thereto.

3. An electron tube according to claim 2, in which each of said conductive means is in the form of an annular coating on the corresponding one of said insulators.

4. An electron tube according to claim 1, in which said conductive means tends to reduce the height of the focussed beam, and additional conductive means are provided for restoring the beam height adjacent said screen electrode means,

5. An electron tube according to claim 1, in which each of said insulator means carries additional conductive elements to neutralize the beam-narrowing efiect of the said conductive means.

6. An electron tube according to claim 1, in which said screen electrode means comprises a series of spaced arcuately-shaped metal plates, and a plurality of other conductive elements are carried by said insulator means one for each of said plates to neutralize the beam-narrowing effect of said conductive means.

'7. An electron tube according to claim 6, in which each of said conductive elements is integrally attached to a corresponding one of said metal plates.

8. An electron tube according to claim 6, in which each of said conductive elements is in the form of a flange carried by a respective one of said plates and extending radially toward the cathode.

9. A channel-defining screen electrode for an electron tube of the focussed rotary radial beam type, comprising an arcuately-curved metal plate having a channel-defining window therein, and a flange at each end for the purpose described.

10. In an electron tube of the focussed rotary beam kind and in combination, a central electron-emitting cathode, metal screen electrode means surrounding said cathode, and a plurality of conductive elements surrounding the ends of thecathode but separate from said screen electrode means and arranged to be excited by a polyphtase current to rotate said beam at a uniform ra e.

11. An electron tube according to claim 10, in which said screen electrode means has a series of channel-defining windows whose total number is non-integrally related to the number of said conductive elements.

12. An electron tube according to claim 10, in which said screen electrode means is in the form of a single continuous metal plate surrounding the cathode.

13. An electron tube according to claim 10, in which said screen electrode means has a series of channel-defining windows, and a corresponding series of output anodes each in radial alignment with a corresponding one of said windows.

14. Electron tube apparatus, comprising, a central electron-emitting cathode, screen electrode means surrounding the cathode and having a series of channel-defining windows, said screen electrode means arranged to be biassed with respect to the cathode to focus the electrons from the cathode into a sheet-like beam, insulator spacers between the cathode and screen electrode means, conductive means adjacent the cathode ends and negatively biassed to inhibit the'irregular charging of said spacers by the electrons from the cathode, and a plurality of other conductive elements between the cathode and screen electrode means and arranged to be excited by a polyphase current to cause the beam to rotate of sald conductlve-means' to hmlt thel'beanr cur.- t s r t; The fo ll owmg references are of record in the 15;: A-ri electron tube according to claim file of this Patent: v V V which-the focussed beam is sub-divided along the 5 UNITED STATES PATENTS length of the cathode into aplurality of sections, Number- Name Date. each section having at-its'upper and lower ends 2 054 3 Krahl Sept 15 1936 a set of said'con'cluctive:mea.ns; and a, plurality of 2- aai 1946 sets of other conductive elements to' control the beam: rbtati'on and to overcome the. tendency of 10 said conductivemeansto limit the beam current.

PAUL W. CHARTON. 

